Apparatus for recording electrical signals



May 249 4 A. `|l.4 TAYLOR APARA'TUS FORMRECORDING ELECTRICAL SIGNALS v Fiid Jan. 2, 1924 gyn/ventola I.

. cent readable, with my system balanced. On the other hand I have found that under the unfavorable4 conditions pointed out signals recorded on a tape with my balanced arrangements were 95 to 100 per cent readable when the same signals recorded in the unbalanced manner could'not be read at all. A good operator can ordinarily receive aurally complete messages when the static is about twice as strong as the signals, assuming the signal note is of a musical tone, for instance, about 800 per second. When the static becomes three to four times as strong as the signal aural rc. ception usually becomes infipossiblen l have successfully recorded signals, 95 to 10()4 per of balancing when the static interference was four times as strong as the signaling.

My invention will be best understood by lreference to the figure of the accompanying drawing, in which I illustrate a balancing system which may be connected to any source of signal currents which have associ ated therewith undesirable interfering currents. In' general the system is divided into two like paths or circuits into which the currents are introduced, the two paths being brought together in the electro-magnetic system of a recorder relay whose response, either mechanical or electrical, or a .combiu vnation of both, is sucently slow to require for motion an integration of a number of cycles or' variations of like kind, and arranged to oppose the resulting mechanical' eii'orts of the interfering currents. L1 and L2, shown in full lines', represent leads or wires from a receiver or other source of signaling currentsassociated with interfering currents, ,as for instance, a radio receiver. With'theswitch S closed, as shown by the full lines, vthese currents are impressed silnultane'ously upon the circuits containing the primary of the transformers T1 and Tl in one of the paths and the primary of the transformer T, and T2 in the other mth. These circuits have coupled to them lters or traps including variable condenser-s C, and C2, the'transformers T and T2 being preferably step-up transformers, I have used ratios of 1 tcl0. .The transformers Tf and T2 pass the currents into the separated vacuum tube unplifiersk VT1 and VTT From -these amplifiers the currents pass through transformers T, and T2 to the vacuum tubes VT1 and VTZ. The plate circuit of Vacuum tube VTI contains electro-magnetic winding RM1 and of vacuum tube VTL. coiitains elcctro-magnctic winding RME. The battery B,L supplies the plate circuit energyiorboth 'of these vacuum tubes. The grid orii ut circuits of these tubes. contain batteryll, and B2 respectively having potentiometers It, and R, for accuu rately obtaining a negative potential or bias on the grids of the tulics, preferably adjustacarrear when no currents are being received. When currents are-received the positive variation will reduce the negative bias of the grids and allow plate currents to flow, while the negative variation ofthe currents will increase the negative bias of the grids still further preventing late current flow during this phase or bali) period. This amounts to a-rectiication of the currents. tromagnets RM1 andRlil'2 are so wound that the plate currents from the two tubes create magnetic fields which act oppositely on the armature A pivotcd at l). The rheostats the amount ot heating current through the filaments of their respective vacuum tubes,'

the heating currents being supplied from the battery B3.y The plate circuit energy of the vacuum' tubes VT, and VT2 is obtained through a variable connection `X tothe battery B4. i y

By varying the condensers C, and C, the circuits containing these "elements can be thrown in or out of tune with the desired signaling currents, and if one of the circuits is closely in tune with signal, currents while the other is materially out of tune, the signal currents will be trapped or filtered out oi' the path containing the tuned circuit and will be permitted to enter the path containing tl'ie detuned circuit. At the same time the interfering currents not generally being of a fixed frequency, will not be stopped by the tuning of the filtered circuits and will enter both paths with substantially the same amplitude and characteristics. These currents will then follow the two paths, one having signal and interfering currents associated and the other having practically only interfering currents, will be rectified in the vacuum tubes V T1 and VTX, anddelivered to the electromagnetic windings RM, and RM, as a rapid succession of one way impulses of plate currents represent ative ot the one half cycles or variations of the original current. It the armature A of the recorder relay together with its con tactor D and other appurtenances, `be made sufficiently low in period compared withv the period orrapidity o-t' variation of the incoming currents, then it will not beresponsive to each variation but will require the integration of the energy of' a plurality of the variations to cause mechanical motion thereof or mechanical effort to create motion. This action may be enhanced 'or made more positive by electrical tuning, as by making the period'of the relaymagnets 'RM1 and RM, low, preferably accomplished by condensers C1 and C2 of' large capacity being placed in shunt with the windings. lVith ordinary commercial windings I have found capacities of 'from 1 to 3 microfarads The elecv ilu. it] and R2', provide for controlling i i give s'ucicntlylow periods to be of material assistance in o taining satisfactory integration. While a relatively mechanically rapil relay may be used with a very slow electrical tuning, I-iiid it preferable to rely upon a combination of bot for best results. The sprn s Z and Zl return the armature A to norma position with contacts D and C open when no signal currents are flowing. When si al currents causethese contacts to close tin' magnet K to operate the recorder arm R to ineke signals on a moving tape G as indicated in the drawing. The record may be made on the tape G in any suitable manner such Vas an ink pen'attached to the recorder arm R. The spring Y cooperates inl the operation of the recorder arm R.,

r in the plate circuits of vacuum tube aud'VT. v I have also shown nay-system arranged to havel delivered `to it currentsl from two' sources such as two radio receivers, 1in-'one of which receivers the signalcurrents` are strong though associated with interfering currents due to the receiver being place closely in tune with the incoming `si als,

while the other receiver has practical y no signal or wealr signal due to being out of tune with the incoming signalbut strong in interfering currents not subject to climi nation through tuning. By vconnecting one of, these receivers lto the Wires or leads L, and L# (shown in dotted lines), and the other receivers to leads L2 and L2 (shown in dotted lines) and opening the switch S v (as illustrated in dotted lines), thel currents are set up inthe two paths. With this 'arrangement it is not necessary toA use the filter circuits 'containing condensers C, and G2- unless it is not possi l extent desired, when further elimination may be obtained by iiltering with the 'filter circuits. This latter method of obtaining two components of currents through the use of two receivers has the disadvantarve that it occupies two frequcncies'and ma e subject to interierenceifrom a perior ical current signal being transmitted on the sec# ond frequency.

I valso findit desirable to include meansv for controlling the amplitudes of the ciirv rents in the two paths, particularly for the purpose of delivering to the relay :for inted trol lts and R4 inshunt with the `primaries of e battery B5 energizes the electroo vacuum` tubesy usedl in series e to reduce the si lnal current in the detuned receiver to t e waneer 'gration the saine amount of energyot inter-y erin currents from e'achpath. This conobtaiii through variable resistances transformers T, and T2. Since the im pedancesrof these'trausforniers are high the resistanccs inu'st be high in order to obtain acontrolof the energy rather than a large loss. There are obviously. other means known to those skilled inthe :art for'obtaining a control ci this lrind.

Hanging described my vnventionl claim l. In a system for recording signals composedot periodical electrical currents in the presence of varyingl electrical currents of an interfering nature the combination of means for separating the currents into two components-one oi which has the signal and interfering currents in association and the other eeinprisingsub'stantially only interfering currents,means for rectifyingthe' currents, shunt connected means -for independently controlling' the amplitude o the two com energy o a plurality of the rectified cycles and variations of said currents into one-way mechanical efforts, said means being adapted tov oppose theeilioitsrcsulting from the sep'- arated'interfering currents, and means for utilizing the resulting unopposed alfort ot said signal currents to record signals.

2. Ina systemv for recording signalscom'- posed of periodical electrical currents in the resence of varying electrical currents of an interfering nature the combination of` two nents, means for integrating the l electrical circuits, means :turintroducing4 the currents into'said circuits, means inone of said circuits for filtering out the signal currents means iiiboth of' said /circuits for rectiiiying the currentsia, derice'for receiving the rectified currents from said circuits and integrating a plurality of lthe rectified cycles and variations into one-way mechanivcal eiiorts, shunt connected means :tor controllinl the amplitude of the currents in each of sai( circuits, and adapted to oppose the,

efforts due to the interfering currents, and

means for utilizing the eort due to tlieunfiltered signal' currents to record'signals. 3.' In a system for recording signals composed of periodical electrical currents in the presence of varying electrical currents of an interfering nature the combination of a circuit containing-y said currents in'association, a parallel circuit containing substantially only interfering currents of i iao ke cha-racterl istics to the interfering currents in said; first p circuit, meansin both circuits for rectifying l the currents, shunt connected means forad- Justing the amplitude of the currents in both circuits, and a. relay into whichv all of the vrectified currents are delivered having an armature Tof period sulciently low with r` e spect to the periods of said currents to iiitegrate the encrgy ofi a plurality of the ias Q9 ranch circuits,

vconnected to eachl of said output circuits, a

differential relay having a pair of windings and a connection between each of said rectiers and one of said windings of said differential relay, and means coupled to each of said first mentioned input circuits for selectively receiving a desired frequency while excluding other frequencies. q

5. .A relay recorder system comprising an audio frequency signal receiving circuit, a pair of audio frequency transformers each having primary and secondary windings, with the nected in series in said audio frequency sig-` nal'receiving circuit, and having the secondary winds thereof connected to separate branch circuitsa diiferential relay havmg a pair of windings and connections between each of said windings and said and tunable step yup transfrequency sigprimary windings thereofA com Leccese former circuits connected in' shunt with each of said primary windings. for yselectively adjusting said 'relay recorder system to res ond to s. particularA frequency while exclu "ng other frequencies.

6. A relay recorder system comprising an audio frequency signal receiving circult, a pair of audio frequency transformers each having primary and secondary windin s, with -the primary windings thereof connected in series in said audio frequency sig- I nal y,receiving circuit, and having the sec-iv y ondary windings thereof connected to `sepay an independent 'elecv" rate branch circuits,

each of said branch tron tube amplifier in circuits, separate electron tube ndetectors connected to each o-f .said amplifiers, a differential relay having a pair of windings, a connection between each of said detectors and one of said windings, means'connected in shunt with each of said amplifiers for.

controlling the amplitude of-the signalin energy supplied to said detectors, an .v means connected in shunt with each'ofvsaid primary windings for selectively receiving signaling energy at one frequency While ex cluding signaling energy at ther frequencies for actuating said differential relay.

,ALBERT H. TAYLOR. 

